﻿/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;
using System.Collections.Generic;
using System.Linq;

#if NET5_0_OR_GREATER
using System.Runtime.InteropServices;
#endif

namespace Apache.Arrow.Adbc.Extensions
{
    internal static class CollectionExtensions
    {
        public static Span<T> AsSpan<T>(this IReadOnlyList<T> list)
        {
            T[]? array = list as T[];
            if (array != null) { return (Span<T>)array; }

#if NET5_0_OR_GREATER
            List<T>? concreteList = list as List<T>;
            if (concreteList != null) { return CollectionsMarshal.AsSpan(concreteList); }
#endif

            return list.ToArray().AsSpan();
        }
    }
}
